Railroad crews working on or in the vicinity of active railroad tracks are susceptible to accidents as a result of not being sufficiently warned of an oncoming train entering the work area. The rail work is typically performed in isolated regions away from crossing areas, and therefore the work crews do not have the benefit of standard crossing signals to warn them of approaching trains. Thus, there lies a need for a reliable warning system for warning maintenance-of-way crews which allows the crew to concentrate on the work at hand while providing adequate warning of oncoming train hazards in order to clear the tracks of tools, equipment and workers to avoid an accident. The railroad crew warning system is further required to be portable and easily set up by the crew in a relatively short period of time. Additionally, the warning system should be of sufficient operational efficiency to activate the warning system only upon the detection of a train to thereby mitigate the natural human tendency to ignore the warning system after false activations.